1. Field of the Invention
This invention relates to the electrical heating of articles, such as test tubes, by means of a heated block having receptacles containing the tubes.
2. Description of the Prior Art
Applicants' assignee, Lab-Line Instruments, Inc., has, commercially manufactured a series of heaters designed for laboratory-type use, which heaters differ from the heating system described and claimed herein fundamentally in the manner in which the temperature of the heated articles is sensed.
Such prior art heaters include a housing which defines in the top thereof an open-top well, closed at the bottom by a base plate which is heated by an electric heater disposed in the housing. One or more carrier blocks formed of a material having a high thermal conductivity, such as aluminum, are removably receivable in the well, each block having a plurality of receptacles formed in its upper face for receiving associated articles to be heated, such as test tubes or the like. The base plate is heated by the heater and the heat is transferred into the block and thereby into the test tubes or other articles received in the block receptacles, the temperature being controlled by suitable controls on the front panel of the housing.
In this prior arrangement, the temperature of the contents of the test tubes is monitored manually by insertion of a thermometer. This technique is somewhat inefficient, requiring manual intervention and requiring the use of a separate thermometer probe which must be maintained and manipulated.